In the conventional art, as an example of a method of measuring a surface shape such as fine waviness in the first surface of a transparent flat plate, a technique disclosed in JP-A-2009-128098 is known. In this measuring method, an image generated when a pattern arranged above a transparent flat plate is reflected in the first surface of the transparent flat plate is captured by a line sensor. Then, on the basis of the obtained image, the surface shape of the transparent flat plate is calculated.